Congo Viruse

Crimean–Congo hemorrhagic fever (CCHF) is a widespread tick-borne viral disease, a zoonosis of domestic animals and wild animals, that may affect humans. The pathogenic virus, especially common in East and West Africa, is a member of the Bunyaviridae family of RNA viruses. Clinical disease is rare in infected mammals, but commonly severe in infected humans, with a 30% mortality rate. Outbreaks of illness are usually attributable to handling infected animals or people.
Congo-Crimean haemorrhagic fever was first observed in the Crimea by Russian scientists in 1944 and 1945. At that time it was established by studies in human volunteers that the aetiological agent was filtrable and that the disease in man was associated with the bite of the tick Hyalomma marginatum. The agent was detected in the larvae and in adult ticks, as well as in the blood of patients during the fever. This agent, presumably a virus, was not maintained in the laboratory and was lost.
Congo virus was first isolated in Africa from the blood of a febrile patient in Zaire in 1956. In 1967 Simpson et al. described 12 cases of a feverish illness of which 5 were laboratory infections; the virus was isolated by the inoculation of blood into newborn mice. Simpson showed that these viruses were similar to the one isolated in 1956. Casals then showed that the viruses isolated in cases of Crimean haemorrhagic fever and the Congo virus were serologically indistinguishable and demonstrated that other virus strains from Central Asia, the USSR and Bulgaria were similar.